Contamination

HST spectrophotometric standards are routinely observed to monitor
throughput stability. Analysis of the high signal-to-noise photometry
in W and M bands indicates that the instrument is photometrically
stable, with measured variations that are <0.4%.

Charge Transfer Efficiency/Extended Pixel Edge Response (CTE-EPER)

The EPER (Extended Pixel Edge Response) method can be used to measure
CCD detector Charge Transfer Inefficiency (CTI)-induced losses via
internal exposures. EPER data consist of short tungsten lamp flat field
exposures in several filters in order to obtain a large range of
illumination levels (from ~100e- to 4000e-). By measuring the signal
profiles as they extend into the trailing overscan region, an
assessment can be made of the CTE level. Please see the most recent report for current plots.

Darks

UVIS Hot Pixels
WFC3/UVIS (Chip 2, Amps C & D)
This plot shows the hot pixel growth between anneals for WFC3/UVIS. The number of hot pixels are plotted as a function of time since the installation of WFC3 on HST, where red lines represent SIC&DH failures, when WFC3 was safed, and the grey/white
regions represent anneal cycles. Note that the implementation of post-flash occurred on day 1246.

Dark Current
WFC3/UVIS (Chip 2, Amps C & D)
Shows the dark current vs. time for WFC3/UVIS. The red lines represent SIC&DH failures, when WFC3 was safed, and the grey/white regions represent anneal cycles. Note that the implementation of post-flash occurred on day 1246.

Dark Current with linear fit to Cy 17 data
Shows the dark current vs. time for WFC3/UVIS. A linear fit to the Cy 17 data is show in magenta, the yellow lines represent the SIC&DH
failures, when WFC3 was safed, the red lines represent the anneals, and the brown vertical line is the switch between SMOV dark (1800 sec)
and Cy 17 darks (900 sec).